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W143

Sensibly equivalent to:
7B7 7H7 CV303 EF22 W148
    
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The W143 is a variable μ amplifier pentode. It is equivalent to the Mullard EF22.
The B8B base with equi-spaced pins and a central locating spigot.
The coating on the inside of the glass, probably to reduce the release of gas from the glass, obscures the inner structure. The mesh screen and the cathode tube can be seen.
A closer view of the top mica.
The wide glass tube envelope is 27 mm in diameter, and excluding the B8B base pins is 62 mm tall.
References: Data-sheet & 1040.

 

Pin Connections
B8B
1
2
3
4
5
6
7
8
h
a
g2
g3,s
-
g1
k
h

 

Absolute Maximum Operating Conditions
Pentode
Vh
Ah
Va
Vs
Vg
mAa
mAs
ra
gm
6.3
0.2
250
100
-2.5
6
1.7
1.2M
2.0
Thanks to Frank Philipse for supplying the above PDF datasheet.
Updated May 24, 2020.
shape:wide.glass.tube construction:all.glass type:pentode age:1940.1950 base:b8b heater:6.3v pins:8 pin:1.h pin:2.a pin:3.g2 pin:4.g3.s pin:5.- pin:6.g1 pin:7.k pin:8.h
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